Miniature pumps, actuators and related devices and methods for making and use

ABSTRACT

A miniature diaphragm pump. The diaphragm is loaded with energy during the exhaust stroke and the loaded energy is released during the pump stroke, which improves the efficiency of the miniature pump. Energy is loaded via a permanent magnet fixed to the diaphragm. The pump includes a processor for dynamically controlling the position of the diaphragm and the performance of the pump.

BACKGROUND OF THE INVENTION

Miniature pumps have been made for applications in microfluidics forfields such as chemical analysis and other “lab-on-a-chip” applications.Many of these miniature pumps are diaphragm pumps driven by anelectromagnetic mechanism. The interaction between a permanent magnetand an electromagnetic coil (capable of having its polarity reversed)causes the diaphragm to reciprocate and drive the pump. The diaphragm istypically fixed to either the coil or to the permanent magnet and otherelement of the electromagnetic pairing is held fixed with respect to thediaphragm.

Such arrangements can operate efficiently when pumping fluid or inconditions where there is not a large pressure differential. However, ifthere is a large pressure differential across the diaphragm of such apump, more power is needed to drive the pump. In the context ofminiature pumps, it can be difficult to send more power to theelectromagnetic mechanism without creating undesirable problem such asheat build-up.

Larger scale pumps deal with large pressure differentials across adiaphragm by using mechanical energy to help propel the diaphragm duringthe pump stroke. For example, while electromagnetic forces alone maydrive the diaphragm during the exhaust stroke, a mechanical spring canhelp drive the diaphragm during the pump stroke. That is, during theexhaust stroke a mechanical spring is compressed and when theelectromagnetic field is reversed the mechanical spring unloads itsloaded energy to return the diaphragm. However, such an arrangement hasits highest energy at the beginning of the pump stroke and loses energyat the same time the diaphragm is encountering high resistance. Further,such mechanical loading is not practical in a miniature pump.

These challenges and others can be addressed by the embodimentsdisclosed herein.

BRIEF SUMMARY OF THE INVENTION

Certain embodiments of the present invention are related to devices andmethods for improving the efficiency of miniature diaphragm pumps and inparticular miniature diaphragm pumps driven by electromagneticactuators.

In some embodiments, the miniature diaphragm pump is loaded with energyduring the exhaust stroke and the loaded energy is released during thepump stroke, which improves the efficiency of the miniature pump.

In some embodiments, a supplemental permanent magnet is fixed to adiaphragm of a miniature electromagnetically driven diaphragm pump. Thesupplemental permanent magnet is separated from a fixed pole magnetduring the exhaust stroke of the pump and is magnetically attracted tothe fixed pole magnet during the pump stroke. Separating the permanentmagnet from the pole magnet loads energy during the exhaust stroke.

Certain embodiments of the present invention include a control systemfor operating a miniature diaphragm pump. The control system can includecontrol, storage, sensing, and I/O components.

Certain embodiments of the present invention include a processor fordynamically controlling the position and/or performance of the diaphragmin the miniature diaphragm pump. In some embodiments, the offset and/orthe gain is dynamically controlled in response to measured operationalparameters in order to achieve desired operational characteristics.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a miniature pump according toan embodiment of the invention.

FIG. 2 illustrates a cross-section of the perspective view of FIG. 1.

FIG. 3 illustrates an exploded perspective view of a miniature pumpaccording to an embodiment of the invention.

FIG. 4 illustrates a close up view of the cross-sectional view of FIG.2.

FIGS. 5A and 5B illustrate a perspective view and a plan view,respectively, of a cross-section of a portion of a miniature pumpaccording to certain embodiments.

FIGS. 6A and 6B illustrate schematics of the mechanism of interactionbetween the actuator and the diaphragm of a miniature pump according tocertain embodiments.

FIG. 7 is a graphical depiction of an efficiency comparison between aminiature electromagnetic diaphragm pump using an additional loadingmagnet according to an embodiment of the invention and anelectromagnetic diaphragm pump without a loading magnet.

FIGS. 8A and 8B illustrate a perspective view and a plan view,respectively, of a cross-section of a portion of a miniature pump bodyaccording to certain embodiments.

FIG. 9A illustrates a control and I/O subsystem including a number ofcontrol, storage and I/O components according to some embodiments of thepresent invention.

FIG. 9B shows a flowchart illustrating a number of steps performed by aprocessor to dynamically control a diaphragm according to pressurevalues measured by a sensor according to some embodiments of the presentinvention.

FIG. 9C illustrates an exemplary evolution over a number of pump cyclesof several parameters described above, according to some embodiments ofthe present invention.

FIG. 9D shows an exemplary sequence of steps performed by a controlsystem to implement an autostart mode.

FIG. 10 illustrates an exploded perspective view of an embodiment of aminiature pump.

FIGS. 11A and 11B illustrate different views of a cross-section of aportion of one embodiment of a blow-off valve.

FIGS. 12A and 12B illustrate exterior views of a blow-off valveaccording to some embodiments of the present invention.

FIGS. 13A and 13B illustrate different views of a lower pump bodyaccording to some embodiments of the present invention.

FIGS. 14A, 14B, and 14C illustrate different views of an upper pump bodyaccording to some embodiments of the present invention.

FIGS. 15A, 15B, and 15C illustrate different views of a lower valveassembly body according to some embodiments of the present invention.

FIGS. 16A and 16B illustrate different views of an upper valve assemblybody according to some embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Before the present devices and methods are described, it is to beunderstood that this invention is not limited to particular embodimentsdescribed. It is also to be understood that the terminology used hereinis for the purpose of describing particular embodiments only, and is notintended to be limiting, since the scope of the present invention willbe limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are now described. All publications mentioned herein areincorporated herein by reference to disclose and describe the methodsand/or materials in connection with which the publications are cited.

Short summaries of certain terms are presented in the description of theinvention. Each term is further explained and exemplified throughout thedescription, figures, and examples. Any interpretation of the terms inthis description should take into account the full description, figures,and examples presented herein.

The singular terms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, reference toan object can include multiple objects unless the context clearlydictates otherwise. Similarly, references to multiple objects caninclude a single object unless the context clearly dictates otherwise.

The terms “substantially,” “substantial,” and the like refer to aconsiderable degree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels or variability of the embodiments describedherein.

The term “about” refers to a value, amount, or degree that isapproximate or near the reference value. The extent of variation fromthe reference value encompassed by the term “about” is that which istypical for the tolerance levels or measurement conditions.

All recited connections may be direct connections and/or indirectoperative connections through intermediary structure.

A set of elements includes one or more elements.

Unless otherwise stated, performing a comparison between two elementsencompasses performing a direct comparison to determine whether oneelement is larger (or larger than equal to) the other, as well as anindirect comparison, for example by comparing a ratio or a difference ofthe two elements to a threshold

FIG. 1 illustrates a perspective view of a miniature pump 10, whichincludes inlet port 12 and outlet port 14. The miniature pump 10includes pump body 11, which can be a single piece or can be formed frommultiple pieces. In FIG. 1, the pump body 11 includes upper body 11 aand lower body 11 b. The miniature pump 10 also includes actuator 15.Preferably, the actuator 15 is an electromagnetic voice-coil typeactuator such as those commonly used in mobile phones and otherelectronic devices.

FIG. 2 illustrates a cross-section of the perspective view of FIG. 1 ofthe miniature pump 10. FIG. 2 illustrates the diaphragm assembly 50,which includes diaphragm 55. FIG. 2 also illustrates the actuatormembrane 5 on the upper surface of the actuator 15. The actuatormembrane 5 is coupled to the diaphragm assembly 50 and drives the motionfor the miniature pump to function.

FIG. 3 illustrates an exploded perspective view of the miniature pump10. FIG. 3 illustrates the diaphragm assembly 50 as including upperspacer 53, diaphragm 55, magnet 57, and housing 59. The upper spacer 53helps define the upper portion of the pumping chamber in which thediaphragm 55 reciprocates. The upper spacer 53 may alternately be acomponent, such as a molded component, of the lower pump body 11 b. Themagnet 57 is attached to the lower surface of diaphragm 55 and alsoattached to the upper surface of the actuator membrane 5. The housing 59is attached to the lower surface of the lower pump body 11 b. The spacer53 is configured to fit within the inner circumference of the uppersection of housing 59. The outer edges of the diaphragm 55 aresandwiched between the lower surface of the spacer 53 and the uppersurface of the inner ring of housing 59 such that the spacer 53 and thehousing 59 cooperate to keep the outer edges of the diaphragm 55 fixed.The edges of the diaphragm 55 are held fixed while the inner portion ofthe diaphragm 55 is able to reciprocate up and down, and the diaphragm55 thereby acts as the volume displacement mechanism of the miniaturepump 10. The components that make up diaphragm assembly 50 should bejoined in a fluid-tight and/or air-tight manner.

FIG. 3 illustrates the lower pump body 11 b, which can be a molded partthat incorporates many of the flow-paths and flow-control features ofthe miniature pump 10. For example, the inlet valve recess 21 a isconfigured to accept the inlet valve 20 a and the outlet valve recess 21b is configured to accept the outlet valve 20 b. Also within lower pumpbody 11 b are openings and ports configured to complement the valve anddiaphragm arrangement and allow for controlled flow of gas or liquidthrough the lower pump body 11 b.

FIG. 3 illustrates a control board 70, a blow-off valve 60, and a sensor80, all of which can be housed in recessed areas within the pump body.In FIG. 3, both the upper pump body 11 a and the lower pump body 11 binclude features configured to house the control board 70, the blow-offvalve 60, and the sensor 80.

Generally speaking, the operation of the inlet valve 20 a and the outletvalve 20 b is similar to a positive displacement diaphragm pumps. Thatis, when the diaphragm is withdrawn away from the inlet port 12, theinlet valve 20 a is also drawn away by negative pressure from upperinlet chamber port 202 a and engages against inlet port offset 201 a.This movement creates a flowpath down through the inlet port 12, throughthe upper inlet chamber port 203 a (see FIG. 8B), across the inlet valve20 a, and down through the lower inlet chamber port 202 a. The negativepressure also draws the outlet valve 20 b into sealing engagement withthe lower outlet chamber port 202 b , which seals the outlet chamber andprevents flow through to the outlet 14.

When the diaphragm 55 begins its return stroke towards the inlet port12, positive pressure forces the inlet valve 20 a away from the inletport offset 201 a and into sealing engagement with the upper inletchamber port 203 a. The positive pressure also forces the outlet valve20 b away from the lower outlet chamber port 202 b and into engagementwith the outlet port offset 201 b. This movement creates a flowpath fromthe diaphragm chamber, through the lower outlet chamber port 202 b,across outlet valve 20 b, through upper outlet chamber port 203 b (seeFIG. 8B) and out through outlet 14.

FIG. 4 illustrates a close up view of the cross-sectional view of FIG.2. In FIG. 4, the inlet valve 20 a is depicted in its closed positionsuch that its upper surface is sealingly engaged against upper inletchamber port 202 a and the outlet valve 20 b is depicted as engagedagainst the outlet port offset 201 b. Further, outlet valve 20 b isdepicted as disengaged from lower outlet chamber port 202 b.

The valves are sized and configured to be movable by the range ofpressure expected from the use environment of the miniature pump 10. Forexample, the valves should have a weight to surface area ratio such thatthey are movable by the flow of liquid or gas when the miniature pump isin use. Further, the valves are made of a material that enables thevalves to sealingly engage against their respective ports when movedinto such as sealing position by liquid or gas flow. Rubber is oneexample of a suitable material for making valves in such a miniaturepump.

FIGS. 5A and 5B illustrate a perspective view and a plan view,respectively, of a cross-section of a portion of a miniature pump 10according to certain embodiments. FIGS. 5A and 5B illustrate the housing59 engaged with a section of lower pump body 11 b. A portion of thediaphragm is shown as engaged to housing 59 and labeled with thereference 55 a. Actually, the diaphragm 55 spans the housing 59 and inthis perspective view would obscure the magnet 57 from view. For thepurposes of these views, only a portion of the diaphragm 55 is shown.The magnet 57 is attached to the actuator membrane 5.

When known diaphragm displacement pumps are connected to a closedchamber in order to pull vacuum on such a chamber, each pump strokerequires successively more energy than the last stroke as the pressuredifference across the diaphragm increases. That is, the greater thevacuum in the closed chamber, the more difficult it is for the diaphragmto travel a full stroke. Generally, pumps are driven with more power inorder to generate longer pump strokes under higher vacuum conditions.

In contrast, pumps according to certain embodiments do not require asmuch of an increase in power to generate longer pump strokes underhigher vacuum conditions because these miniature pumps are loaded on theexhaust stroke. In contrast to previously known positive displacementdiaphragm pumps, the miniature pump 10 includes the magnet 57, whichfunctions to load the pump stroke of the miniature displacement pumpduring the exhaust stroke. The actuator membrane 5 can be driven using asinusoidal signal such that the actuator membrane 5 reciprocates betweenan upper position and a lower position. Since the actuator membrane 5 isattached to the diaphragm 55, the reciprocation of the actuator membrane5 causes a similar reciprocation of the diaphragm 55. When the actuatormembrane 5 and diaphragm 55 reciprocate away from the pump body 11, thediaphragm motion is expanding the size of the diaphragm chamber anddrawing gas or liquid within the chamber in a pump stroke. When theactuator membrane 5 and diaphragm 55 reciprocate toward the pump body11, the diaphragm motion is contracting the size of the diaphragmchamber 54 in an exhaust stroke. The inlet valve 20 a and the outletvalve 20 b are, of course, moving in concert with such pump strokes andexhaust strokes to allow gas or liquid to flow one way through theminiature pump from the inlet to the outlet.

The actuator 15 can be an electromagnetic voice coil, which includes anelectromagnetic drive element coupled to the actuator membrane 5. Such avoice coil actuator performs essentially like a loudspeaker, such thatwaveform signals sent to the electromagnetic drive element drive theactuator membrane in a pattern generated by the waveform.

FIGS. 6A and 6B illustrate schematics of the mechanism of interactionbetween the actuator and the diaphragm. The actuator 15 includes anactuator base 15 b, an actuator membrane 5, an actuator pole magnet 7,and actuator coil 3. The actuator pole magnet 7 is fixed to the actuatorbase 15 b. The actuator coil 3 is fixed to the underside of the actuatormembrane 5. The magnet 57 is a permanent magnet and is fixed to theupper surface of the actuator membrane 5 and to the underside of thediaphragm 55. In some cases, the position of the magnet 57 is adjustableup and down with respect to the actuator membrane 5, but in FIGS. 6A and6B it is depicted as fixed to the actuator membrane 5.

During the pump stroke, electric current is applied to the actuator coil3 to create an electromagnetic field that attracts the actuator coil 3to the actuator pole magnet 7. The actuator coil 3 is fixed to theactuator membrane 5, which is connected to the diaphragm 55. Thus, thediaphragm 55 is pulled away from the diaphragm chamber 54, therebyincreasing the volume of the chamber and drawing air or liquid throughthe inlet valve and into the diaphragm chamber in a pump stroke.

Referring still to FIGS. 6A and 6B, the magnet 57 is oriented to bemagnetically attracted to the actuator pole magnet 7. During the pumpstroke when the diaphragm 55 is pulled away from the diaphragm chamber54, the magnetic attraction between the magnet 57 and the actuator polemagnet 7 helps pull the diaphragm 55 and the actuator membrane 5 morefully back towards the actuator pole magnet 7 than if the magnet 57 wasnot present in this position. This is especially helpful at high suctionwhere the diaphragm 55 would not ordinarily be able to travel as fardownward because of the pressure drop across the diaphragm 55. That is,at low levels of negative pressure in the diaphragm chamber 54, there islow resistance to pulling the diaphragm 55 away from the diaphragmchamber 54. Thus, the electromagnetic force generated by low power inthe actuator coil 3 is sufficient to drive the pump stroke. However, athigher levels of negative pressure in the diaphragm chamber 54, there ishigher resistance to pulling the diaphragm 55 and therefore higher powerwould be required. The magnet 57 is helpful in this context because itadds magnetic force to pull the diaphragm 55 down without requiringadditional power since the magnet 57 is a permanent magnet.

FIG. 6B depicts the exhaust stroke, in which electric current is appliedto the actuator coil 3 to create an electromagnetic field that repelsthe actuator coil 3 from the actuator pole magnet 7. Repelling theactuator coil 3 forces the actuator membrane 5 and the diaphragm 55towards the diaphragm chamber 54, which reduces the volume of thediaphragm and drives air or liquid through the outlet valve in anexhaust stroke. During this exhaust stroke, the magnet 57 is also pushedaway from the actuator pole magnet 7. That is, the electromagnetic forceis sufficient to repel the actuator coil 3, and all the components fixedto it (such as the actuator membrane 5, the magnet 57, and the diaphragmmembrane 55) away from the actuator pole magnet 7.

Advantageously, the magnet 57 is moved away from the actuator polemagnet 7 during the exhaust stroke. This is an advantage because thediaphragm 55 encounters comparatively low resistance during the exhauststroke as gas or liquid is displaced from the diaphragm chamber 54.Thus, the exhaust stroke separates the magnet 57 from the actuator polemagnet 7 with relatively low additional power requirement than if themagnet 57 was not on the diaphragm 55. Then, during the pump stroke, theseparation between the magnet 57 from the actuator pole magnet 7provides additional magnetic force as described above. As a result, theminiature pump is able to operate more efficiently at low power than aconventional electromagnetic diaphragm pump.

FIG. 7 is a graphical depiction of an efficiency comparison between anminiature electromagnetic diaphragm pump using an additional “loading”magnet according to an embodiment of the invention and anelectromagnetic diaphragm pump without a loading magnet. This graphplots the physical displacement, or stroke length, of the diaphragm as afunction of the number of pump strokes as the electromagnetic pump isused to evacuate a closed chamber. Further, this graph assumes that thepumps are driven at a generally constant power, although the benefit ofthe loading magnet is not limited to constant power applications.Because the pumps in the graph are evacuating a closed chamber, thepressure difference across the diaphragm increases with each pump strokeas the negative pressure increases inside the closed chamber. While theloaded and the unloaded diaphragm both travel at or near their fulldisplacement during the initial pump strokes, the efficiency of thepumps diverges as negative pressure increases. The unloaded diaphragm(labeled as “no loading”) has a rapidly diminishing pump stroke suchthat it becomes comparatively inefficient at higher pump strokes. Theloaded diaphragm, in contrast, is able to be physically displaced to agreater degree in this constant power application because of the passivemagnetic loading force of the permanent magnet fixed to the diaphragm.

The relative strength of the magnetic forces among the actuatorcomponents (i.e., the electromagnetic coil and the pole magnet) and thediaphragm magnet can be used to tune the efficiency of the miniaturepump. For example, a stronger diaphragm magnet will provide more loadedenergy to the pump stroke of the diaphragm when separated from the polemagnet, but will also require more power to be separated during theexhaust stroke.

In some embodiments, the diaphragm magnet is fitted with an adjustmentmechanism that allows the separation between the diaphragm magnet andthe pole magnet to be varied. For example, the diaphragm magnet could behoused within a recess fixed to the upper surface of the actuatormembrane. The diaphragm magnet could rest atop a tapered adjustmentscrew such that when the screw is turned one direction the magnet movescloser to the actuator membrane and when the screw is turned theopposite direction the magnet moves farther from the actuator membrane.

Advantageously, magnetic fields are sensitive to distance. The strengthof the magnetic field between the two permanent magnets (the actuatorpole magnet and the diaphragm magnet) can decay following the inversecube of the distance from the source. That is, if D is the distancebetween the magnets and F is the strength of the forces, then F=1/D³.This is advantageous for embodiments of the invention because the forceis much higher when the permanent magnets are closer, such as at themaximum displacement of the diaphragm during the pump stroke. And, theforce is much lower at the minimum displacement of the diaphragm duringthe exhaust stroke. The loaded miniature pump designs of embodiments ofthe invention can operate with significantly more efficiency thanunloaded pump designs because of this inverse relationship between forceand distance.

In accordance with some embodiments, the miniature pump preferably isabout 12 to 20 mm long, about 10 to 15 mm wide and about 3 to 9 mm high,more preferably about 18 mm long, about 12 mm wide and about 7 mm high.The mass is preferably about 1 to 5 grams, more preferably about 3grams. The miniature pump preferably operates with a voltage betweenabout 3.5 to 5 volts, peak current when running of about 100 to 200 mA,and standby current of about 20 to 40 mA. The miniature pump isself-priming and preferably is less than about 90 dB two inches away,more preferably, less than about 70 dB two inches away. The miniaturepump preferably has a peak suction of about −6 in Hg, more preferablyabout −8 in Hg. The suction rate is preferably about 0 to −6 in Hg inless than about 10 seconds with 10 mL volume of air, more preferablyabout 0 to −8 in Hg in less than about 10 seconds with 10 mL volume ofair.

FIGS. 8A and 8B illustrate a perspective view and a plan view,respectively, of a cross-section of a portion of the pump body 11according to certain embodiments. In these views, upper channel 52 a andlower channel 52 b are in fluid connection from the diaphragm chamber tothe blow-off valve 60 and the sensor 80. The valve channel 62 and thesensor channel 82 are in fluid connection with upper channel 52 a. Thesechannels allow for monitoring and control of the pressure in thediaphragm chamber via the sensor 80 and the blow-off valve 60. Thechannels can be designed as part of the molded pump body 11 sections,can be drilled into the pump body 11 after molding, or can be tubes orother conduits that are included in an overmolding step or duringassembly of the pump body.

The blow-off valve 60, the sensor 80, and the control board 70 worktogether in a closed loop control system for monitoring and adjustingthe performance of the miniature pump. In one example, the closed loopcontrol systems can be programmed to maintain a level of negativepressure within the diaphragm chamber. That is, the sensor continuouslymonitors the pressure level in the diaphragm chamber and provides thatdata to the control board. The firmware (or software) on the controlboard can compare the data to the programmed pressure level and thensend power to the actuator to drive the miniature pump to increase thepressure or send a signal to the blow-off valve to release negativepressure. In another example, a pre-programmed or user-selected suctionprofile can be generated using the closed loop control system. That is,rather than seeking a set level of negative pressure, the closed loopcontrol system seeks a time-dependent pattern of pressure levels bycontinuously comparing the negative pressure level in the diaphragmchamber with the time-dependent level specified in the profile. Theblow-off valve or the pump can then be activated as needed.

In another example, the closed loop control system can help optimize theefficiency of operation and reduce noise levels. In this example, thefirmware uses a look-up table to find optimal operating conditions forthe miniature pump at a given level of negative pressure. At a givenpressure the miniature pump may operate most efficiently at a certainpower signal profile. That is, a particular shape of the signal waveform(e.g., the amplitude and frequency of a sinusoidal signal) may allow theminiature pump to operate more quietly than another similar shape at agiven pressure. Generally, noise in the miniature pump is generated bythe diaphragm hitting the walls of the diaphragm chamber and by thevalves hitting the walls of their valve recesses and offsets. Bycalibrating the position of the diaphragm and valves at given powerlevels and pressure levels and cross-referencing those positions againstpower and pressure levels in a look-up table accessible to the firmware,the miniature pump can be operated in a way that reduces or eliminatedvalve and/or diaphragm noise. Further, reducing or minimizing diaphragmand valve noise increases the efficiency of the miniature pump sinceless energy is lost to the pump body through collisions between thevalves and/or diaphragm and the pump body.

Another advantage of the closed loop control system is that the blow-offvalve can be activated under certain conditions. For example, if thenegative pressure exceeds a certain level, the firmware can activate theblow-off valve to allow air into the diaphragm chamber. As anotherexample, if the valve temperature rises above a certain level (asdetected by a temperature sensor integrated into the miniature pump andin communication with the control board), the firmware can activate theblow-off valve.

Generally, the control and sensing components of the miniature pump canreside within the pump housing or can be remote from the pump. That is,a processor and sensor can be located away from the actual pump body andstill be able to provide the sensing and control features describedherein. Also, the blow-off valve maybe located remotely from the pumpbody provided it has the fluid connection necessary to provide thepressure relief performance. Thus, the closed loop feedback system canexist in a system of physically separate components that arefunctionally interconnected.

FIG. 9A illustrates a control and I/O subsystem 220 including a numberof control, storage, and I/O components according to some embodiments ofthe present invention. Some of the components may be part of the controlboard 70, while others, such as a set of user input-output (I/O) devices232, may be electrically connected to, but physically separated from,the control board 70. In some embodiments, the control board 70 includesa processor 224, a memory 226, a set of storage devices 234, and a setof external communications interface controller(s) 230, andanalog-to-digital (A/D) converter 234, and a digital-to-analog (D/A)converter 236, all interconnected by a set of buses 250. Analogcircuitry 238 is connected to A/D converter 234. Analog circuitry 238includes components such as amplifiers and filters configured to performanalog processing such as amplification and filtering on analog signalsreceived by the control board 70 from external sensors. Analog circuitry240 is connected to D/A converter 236. Analog circuitry 240 includescomponents such as amplifiers configured to perform analog processingsuch as amplification on analog signals received from D/A converter 236.A/D converter 234 and D/A converter 236 connect the processor 224 to theblow-off valve 60, sensor 80 and diaphragm 55, as described below.

In some embodiments, the processor 224 comprises a microcontrollerintegrated circuit or other microprocessor configured to executecomputational and/or logical operations with a set of signals and/ordata. Such logical operations are specified for the processor 224 in theform of a sequence of processor instructions (e.g. machine code or othertype of software). A memory unit 226 may comprise random access memory(RAM, e.g. DRAM) storing data/signals read and/or generated by processor224 in the course of carrying out instructions. The processor 224 mayalso include additional on-die RAM and/or other storage.

Storage devices 228 include computer-readable media enabling thenon-volatile storage, reading, and writing of software instructionsand/or data, such as EEPROM/flash memory devices. Communicationsinterface controller(s) 230 allow the subsystem 220 to connect todigital devices/computer systems outside the control board 70 throughwired and/or wireless connections. For example, wired connections may beused for connections to components such as user I/O devices 232, whilewireless connections such as Wi-Fi or Bluetooth connections may be usedto connect to external components such as a smartphone, tablet, PC orother external controller. Buses 250 represent the plurality of system,peripheral, and/or other buses, and/or all other circuitry enablingcommunication between the processor 224 and devices 226, 228, 230, 234,and 236. Depending on hardware manufacturer, some or all of thesecomponents may be incorporated into a single integrated circuit, and/ormay be integrated with the processor 224.

User I/O devices 232 include user input devices providing one or moreuser interfaces allowing a user to introduce data and/or instructions tocontrol the operation of subsystem 220, and user output devicesproviding sensory (e.g. visual, auditory, and/or haptic) output to auser. User input devices may include buttons, touch-screen interfaces,and microphones, among others. User output devices may include one ormore display devices, speakers, and vibration devices, among others.Input and output devices may share a common piece of hardware, as in thecase of touch-screen devices.

In some embodiments, the processor 224 controls the positioning of thediaphragm 55 by using analog circuitry 240 to dynamically control adirect current (DC) offset and a gain of a diaphragm drive signal. Theoffset level controls the resting position of diaphragm 55, while thegain controls the amplitude of a sinusoidal or other periodic signalwaveform which determines the amplitude of the excursion of thediaphragm 55 from its resting position. The offset and gain may becontrolled dynamically in response to measured operational parameters inorder to achieve desired operational characteristics, as describedbelow. In particular, the offset and/or gain may be changed in responseto variations in pressure measured using the sensor 80.

As the pump operates over time in a given evacuation sequence, thepressure differential across the diaphragm 55 generally increases.Without changes in offset and gain, the increasing pressure differentialwould lead to a gradual change in the resting position of the diaphragm55. The increase in pressure difference leads to changes in the optimaloffset and gain values for achieving particular pump characteristicssuch as maximum rate of increase in pressure difference (pumping speed),minimum current consumption (or maximum energy efficiency), or minimalnoise. In some embodiments, the offset is decreased (or increased) overtime to compensate for the effect of the increased pressure differentialacross diaphragm 55 on the resting position of diaphragm 55. The offsetand gain values may be varied according to a pressure lookup table,and/or according to dynamically measured changes in one or moreparameters of interest, such as a pressure difference (delta) observedover one pump cycle.

FIG. 9B shows a flowchart illustrating a number of steps performed byprocessor 224 to dynamically control the diaphragm 55 according topressure values measured by the sensor 80 according to some embodimentsof the present invention. In a step 300, processor 224 receives aninstantaneous pressure value measured by the sensor 80 for the currentpump cycle. In a step 302, the pressure difference (delta) relative to apreviously-measured pressure value (e.g. a pressure value measured forthe immediately-prior pump cycle) is determined. In a step 304, thedetermined pressure delta is compared to one or more reference values,in order to determine a magnitude and/or sign of offset and/or gainadjustments to be made for subsequent pump cycles. A reference value maybe equal to or otherwise determined according to a pressure deltameasured for an immediately-previous pump cycle, or an expected pressuredelta for a given measured pump pressure as retrieved from a calibrationtable or other storage. Performing such a comparison may comprisesubtracting a reference value from the measured pressure delta.

In a step 306, it is determined whether the offset is to be updated forthe next pump cycle. In some embodiments, the determination whether toupdate the offset may be performed independently of the pressure deltacomparison described above. For example, offset updates may be performedduring certain blocks of cycles while gain updates are performed duringother blocks of cycles, in order to attempt to separate the measuredeffects on pressure delta of offset and gain changes. In anotherexample, offset and gain updates may be performed on alternating pumpcycles. In some embodiments, both offset and gain updates may beperformed during at least some pump cycles. In some embodiments, adetermination whether to update the offset may be performed according tothe pressure delta comparison described above, if it is determined thatan offset change is likely to improve pump performance.

In a step 308, the offset is updated according to the pressure deltacomparison performed in step 304. In some embodiments, updating theoffset comprises incrementing or decrementing the offset by a fixed step(e.g. ±1) if it is determined that such incrementing/decrementing islikely to lead to improve pump performance on the next pump cycle.

In a step 310, is it determined whether the gain is to be updated forthe next pump cycle. Step 310 may be performed in a manner similar tothat described above for step 306. Subsequently, in a step 312, the gainis updated according to the pressure delta comparison performed in step304. In some embodiments, updating the gain comprises incrementing ordecrementing the gain by a fixed step (e.g. ±1) if it is determined thatsuch incrementing/decrementing is likely to lead to improve pumpperformance on the next pump cycle.

FIG. 9C illustrates an exemplary evolution over a number of pump cyclesof several parameters described above, according to some embodiments ofthe present invention. The x-axis denotes time (or pump cycles), whilethe y-axis illustrates the various parameter values. An estimated offset400 represents an offset chosen according to a predetermined calibrationtable, independently of dynamically-measured pressure values. Adynamically-determined offset 402 represents an offset chosen accordingto dynamically-determined pressure delta values as described above. Avacuum level (compression) 404 represents the measured vacuum level, orpressure differential across the diaphragm 55. A gain 408 represents again. A pressure delta 406 represents the pressured delta observed overeach pump cycle, i.e. effectively the derivative of the vacuum level404.

As illustrated in FIG. 9C, the vacuum level 404 increases over time asthe pump operates, with the per-cycle pressure delta 406 generallydecreasing over time as the pump works against an increasing diaphragmpressure differential. The gain 408 suitable for maintaining the pump inan optimal operating regime increases over time. At each time point, alow gain leads to a suboptimal displaced volume, while a high gain canlead to a loss of efficiency and/or noise if the diaphragm 55 collideswith an external structure at the end of its excursion. At the sametime, the offset corresponding to an optimal operating regime decreasesover time, compensating for the effect of the pressure differentialacross the diaphragm 55 on the central position of diaphragm 55. Thedynamically-determined offset 402 may differ from thepreviously-determined (calibrated) offset 400, for example due todifferences between the individual characteristics of the pump (whichdetermine the offset 402) and the general pump characteristics used togenerate the calibration data determining the estimated offset 400. Forexample, while the general offset 400 decreases monotonically, thedynamically-determined offset 402 occasionally increased. Also, thedynamically-determined offset 402 at times decreased at a different ratethan the general offset 400. Using dynamically-determined offset 402facilitates the manufacture of pumps using less-stringent manufacturingtolerances, as optimal pump operation is less dependent on any mismatchbetween individual pump characteristics and the general pumpcharacteristics reflected in calibration data.

In some embodiments, a pump and associated control system as describedabove may be used to generate pressure patterns other than amonotonically-increasing one such as the one illustrated in FIG. 9C. Forexample, alternating pressure (suction) periods may be used byalternating periods of increased pumping (and/or decreased associatedrelief valve use) with periods of decreased or stopped pumping (and/orincreased associated relief valve use).

FIG. 9D shows an exemplary sequence of steps performed by a controlsystem to implement an autostart mode. In a step 500, processor 224receives a current measured pressure value while the pump is off. In astep 502, processor 224 compares the measured pressure to apredetermined positive threshold. Detecting a high level of positivepressure indicates that the chamber to be evacuated has been engaged andsomewhat sealed. If the measured pressure is not above the threshold,the process returns to step 500. If the measured pressure is above thethreshold, processor 224 starts the pump autostart process by turning onthe pump (step 504). A current pressure value for the present pump cycleis received in a step 506, and compared to a prior pressure value in astep 508. In a step 510, it is determined whether the measured pressurevalue(s) indicate that the chamber seal has been breached. For example,a sudden large drop in pressure or a return to atmospheric pressure mayindicate that the chamber no longer sealed. If no major loss of seal isdetected, the offset and/or gain are adjusted as described above (step512), and the process returns to step 506 to receive a pressure valuefor the next pump cycle. If major loss of seal is detected, the pump isturned off (step 514), and the process returns to step 500 to allowdetecting a new engagement of a chamber.

In some embodiments, step 512 may include turning on and off the pump soas to maintain a certain level of negative pressure. Step 512 mayinclude monitoring parameters such as the fraction of time that the pumpis on or the pump pressure slow to determine whether to increase ordecrease the pump's activity. The pump then self-regulates to maintain acertain level of negative pressure.

FIG. 10 illustrates an exploded perspective view of an embodiment of aminiature pump 1010. The miniature pump 1010 includes an actuator 1015,which can be an electromagnetic voice-coil type actuator such as thosecommonly used in mobile phones and other electronic devices. Attached tothe actuator 1015 is the lower body 1011 b, which contains the diaphragmassembly as described previously herein. FIG. 10 specifically depictscertain elements of the diaphragm assembly, including the magnet 1057and the diaphragm 1055. The lower body 1011 b and the lower valveassembly body 1200 b together form the diaphragm chamber as describedelsewhere herein. FIG. 10 further illustrates lower body 1011 bsupporting the control board 1070 via the control board mount 1070 m andcontrol board wires 1071 a, 1071 b extending from the control board1070, providing electrical connectivity to the electromagnetic featuresof the diaphragm assembly. Also present on the control board 1070 arethe sensor 1080, which has the sensor gasket 1085 forming a seal betweenthe sensor 1080 and the upper body 1011 a, and the blow-off valve 1060.The blow-off valve diaphragm 1065 is illustrated in FIG. 10, while theupper sections of the blow-off valve, including its exit port, are notspecifically pictured.

Still referring to FIG. 10, lower valve assembly body 1200 b is attachedto the upper surface of the outer ring of diaphragm 1055 in the mannerdescriber herein (see, for example, FIGS. 5A, 5B, 6A, and 6B and therelated description). The lower valve assembly body 1200 b can includethe valve recesses, inlet ports, and sealing surfaces necessary toprovide the valve action described herein. These features can beintegrally formed into the lower valve assembly body 1200 b, such as byinjection molding a unitary part, they can be formed from multiplemolding process, or they can be fabricated into the lower valve assemblybody 1200 b by cutting or machining or the like. The lower valveassembly gasket 1205 b is placed between lower valve assembly body 1200b and upper valve assembly body 1200 a and provides a fluid tight sealto the valve chambers. The inlet valve 1020 a and outlet valve 1020 bcan float within the valve chambers and function as described elsewhereherein.

Again still referring to FIG. 10, upper valve assembly body 1200 a issimilar to lower valve assembly body 1200 b in that it can include thevalve recesses, inlet ports, and sealing surfaces necessary to providethe valve action described herein and such features can be formed in thesame variety of ways described for lower valve assembly body 1200 b.Further, the fluid flow paths necessary to provide connections among thevalve chambers, pressure sensor, and blow-off valve can be formed inupper valve assembly body 1200 a. The upper valve assembly gasket 1205 acan form the upper boundary of some of these flow paths and provides aseal between the upper valve assembly body 1200 a and the upper body1011 a. The upper body 1011 a, in turn, can also have flow paths, whichin FIG. 10 are depicted as upper body channels 1008. The upper valveassembly gasket 1205 a and the upper body seal 1009 for the lower andupper boundaries, respectively, for certain flow paths. Further, thecutouts in the upper valve assembly gasket 1205 a provide a fluidconnection to the inlet port 1012 and outlet port 1014 on the upper body1011 a. Screws 1001 are used in the final assembly of the miniature pump1010, but of course other methods of securing the upper body 1011 a tothe lower body 1011 b can be used.

The flow paths in the upper body 1011 a provide several connections,such as: (1) a connection between the blow-off valve and the inlet portof the miniature pump; (2) a connection between the blow-off valve andthe outlet port of the miniature pump; and (3) a connection between thepressure sensor and the suction chamber.

FIGS. 11A and 11 B illustrate different views of a cross-section of aportion of one embodiment of a blow-off valve. The upper surface of theblow-off valve diaphragm 1065 engages a port on the outer case of theblow-off valve (which is not pictured). The underside of the blow-offvalve diaphragm 1065 is secured to a blow-off valve attractor plate1068, which is formed from a ferrous material. Below the blow-off valveattractor plate 1068 is the blow-off valve yoke 1067 and the blow-offvalve coil 1069, which cooperate to provide electromagnetic forces thatcan attract the blow-off valve attractor plate 1068. The blow-off valvediaphragm 1065 is formed such that in its resting state it forms a sealagainst the port on the blow-off valve. When current is run through theblow-off valve coil 1069, the blow-off valve attractor plate 1068 ispulled down, which in turn pulls the blow-off valve diaphragm 1065 awayfrom its sealed position. The blow-off valve yoke 1067, blow-off valvecoil 1069, and blow-off valve attractor plate 1068 are housed within theblow-off valve case 1061. FIGS. 12A and 12B illustrate exterior views ofthe blow-off valve 1060, including the blow-off valve port 1062 andblow-off valve case 1061.

The blow-off valve diaphragm 1065 can be formed from materials such assilicone rubber or its equivalents. The blow-off valve attractor plate1068 and the blow-off valve yoke 1067 can be formed from alloys withcomparatively high magnetic permeability, such as a nickel-iron alloy.The blow-off valve coil 1069 can be formed from winding copper or otherconductive wire. The blow-off valve case 1061 can be formed from apolymer-based material, such as a glass-filled polycarbonate.

The blow-off valve functions by having a minimum preload that pressesthe diaphragm against the valve port to ensure that the valve is closedprior to initiating suction. The preload can be chosen by using adiaphragm material with sufficient elastic modulus such that thediaphragm remains engaged against valve port in the assembled state. Insome embodiments, the blow-off valve can further include a non-magneticcompression spring within the electromagnet assembly that always pushesup on the attractor plate. In this scenario, the diaphragm would bedesigned to be as flexible as possible and preload could vary inaccordance with the tolerances associated with the spring constant andthe free length.

Because this electromagnetic blow-off valve operates within a miniaturepump that itself is driven by electromagnetic forces, it is necessary totake into account the overall magnetic fields experience by theattractor plate. The valve diaphragm should be stiff enough to not beaffected by such peripheral magnetic forces. That is, the diaphragmshould resist unwanted displacement via interaction between theattractor plate coupled to the diaphragm and the peripheral magneticfields. Yet, a stiffer diaphragm requires a stronger local magneticfield to displace it and the attractor plate. One method to achieve adesirable local magnetic field is to optimize the number of coil turnsin the blow-off valve coil. A greater number of coil turns can beachieved by growing the overall electromagnet in height or diameter.While it is more space efficient to grow in height (resistance increasesmore slowly given lower total wire length which can prevent having tojump to a lower gauge wire), increases in the outer diameter can alsoprovide space for more coils, which may utilize the available enclosurespace more effectively.

In some embodiments, the maximum current available to the electromagnetis assumed to be 300 mA. This is based on limitations of the battery (1C max). If higher currents could be sourced, the resistance of thecomponent (current 10-12 ohms) would also have to be reduced given theassumed minimum battery voltage of 3.0 V for a miniature pump. Ingeneral, the current draw of the blow-off valve should be monitoredaccording to the application of the miniature pump.

The term “blow-off” valve as used herein refers generally to a type ofvalve used to control or limit the pressure in a system or vessel. Suchvalves may also be known as relief valves, safety valves, and the like,and certain embodiments herein encompass such valves regardless of howthey are named.

FIGS. 13A and 13B illustrate different views of a lower pump body 1011 baccording to certain embodiments. The lower pump body 1011 b includes acutout that forms a diaphragm spacer 1053. The edge of the diaphragmcontacts the edge of the diaphragm spacer 1053 and is thereby spacedaway from the actuator membrane of the actuator that is attached to theunderside of the lower pump body 1011 b.

FIGS. 14A, 14B, and 14C illustrate different views of an upper pump body1011 a according to certain embodiments. The upper pump body 1011 aincludes upper body channels 1008, which connect the ports 1012 and 1014to the sensor area and the blow-off valve area of the upper pump body1011 a. The upper pump body 1011 a includes a sealing feature 1206. Asealing feature 1206 generally circumscribes the areas of the upper pumpbody 1011 a the areas of the upper pump body 1011 a in which fluid ishandled. The sealing feature 1206 can be a raised area, such as a ridge,that mechanically interacts with a gasket to form a reliable seal aroundthe fluid handling area.

FIGS. 15A, 15B, and 15C illustrate different views of an upper valveassembly body 1200 a according to certain embodiments. The upper valveassembly body 1200 a includes ports, recesses and offsets similar tothose described elsewhere herein. FIG. 15A depicts a semi-transparentperspective view of the lower surface of the upper valve assembly body1200 a and FIG. 15B depicts a plan view of that same surface. The uppervalve assembly body 1200 a includes inlet valve recess 1021 a and outletvalve recess 1021 b, which provide a seating area for the inlet valveand outlet valve, respectively. The inlet and outlet valves interactwith the upper inlet chamber port 1203 a and upper outlet chamber port1203 b to provide the valved pumping action described herein. Further,the upper valve assembly body 1200 a includes outlet port offset 1201 b.A sealing feature 1206 is present on this lower surface of the uppervalve assembly body 1200 a to provide improved sealing to the lowervalve assembly gasket 1205 b and separation of the inlet and outletareas. FIG. 15C depicts the upper surface of the upper valve assemblybody 1200 a, having the upper inlet chamber port 1203 a and upper outletchamber port 1203 b. A sealing feature 1206 is present on this uppersurface of the upper valve assembly body 1200 a to provide improvedsealing to the upper valve assembly gasket 1205 a and separation of theinlet and outlet areas.

FIGS. 16A and 16B illustrate different views of a lower valve assemblybody 1200 b according to certain embodiments. FIG. 16A depicts asemi-transparent perspective view of the upper surface of the lowervalve assembly body 1200 b and FIG. 16B depicts a plan view of that samesurface. The lower valve assembly body 1200 b includes inlet valverecess 1021 a and outlet valve recess 1021 b, which provide a seatingarea for the inlet valve and outlet valve, respectively. The inlet andoutlet valves interact with the lower inlet chamber port 1202 a andlower outlet chamber port 1202 b to provide the valved pumping actiondescribed herein. Further, the upper valve assembly body 1200 a includesinlet port offset 1201 a. A sealing feature 1206 is present on thisupper surface of the lower valve assembly body 1200 b to provideimproved sealing to the lower valve assembly gasket 1205 b andseparation of the inlet and outlet areas.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiment disclosed, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A miniature pump, comprising: a voice coil actuator [15] comprising asupport member, an electromagnetic coil [3], and a pole magnet [7]wherein the electromagnetic coil is coupled to the support member; adiaphragm [55] coupled to the support member, wherein motion of thesupport member drives motion in the diaphragm with respect to a chamber[54]; and a permanent magnet [57] coupled to the diaphragm.
 2. Theminiature pump of claim 1 wherein the permanent magnet and the polemagnet are separated by a first distance, which increases to a seconddistance when the electromagnetic coil repels the pole magnet.
 3. Theminiature pump of claim 1 wherein the magnetic poles of each of the polemagnet and the permanent magnet are arranged such that the pole magnetand the permanent magnet are magnetically attracted to each other. 4.The miniature pump of claim 1 wherein the pole magnet and the permanentmagnet are arranged with the electromagnetic coil in a space betweenthem.
 5. The miniature pump of claim 1 further comprising a processor[224] for dynamically controlling the position of the diaphragm.
 6. Theminiature pump of claim 5 wherein the processor dynamically controls thediaphragm in response to measured data.
 7. The miniature pump of claim 5further comprising a sensor [80, 1080] for measuring data.
 8. Theminiature pump of claim 6 wherein the data is pressure.
 9. The miniaturepump of claim 6 wherein the data is diaphragm position.
 10. Theminiature pump of claim 5 wherein the processor dynamically controls adirect current offset in an electrical signal.
 11. The miniature pump ofclaim 5 wherein the processor dynamically controls a direct current gainin an electrical signal.
 12. The miniature pump of claim 1 furthercomprising a processor [224] for initiating an autostart process. 13.The miniature pump of claim 12 further comprising a sensor [80, 1080]for measuring pressure.
 14. The miniature pump of claim 13 wherein theprocessor initiates the autostart process in response to a pressurechange measured by the sensor.
 15. The miniature pump of claim 13wherein the processor turns off the pump in response to a pressurechange measured by the sensor.
 16. The miniature pump of claim 1 furthercomprising a blow-off valve [60, 1060].
 17. The miniature pump of claim16 wherein the blow-off valve is opened in response to a measured changein temperature.
 18. The miniature pump of claim 1 wherein the permanentmagnet maintains a fixed distance from the electromagnetic coil duringreciprocation of the diaphragm.
 19. The miniature pump of claim 1wherein the permanent magnet and the pole magnet are separated by adistance and that distance is adjustable via an adjusting member.